The use of photochemical techniques has generated substantial interest in the application of reacting temperature sensitive compounds. Through the use of lightsensitive reactant solutions and photocatalysts, reactions can be carried out in temperatures substantially less than those normally required for conventional thermally activated reactions and with substantially increased rates. As such it is possible to accelerate the reactions beyond those normally associated with conventional reaction techniques.
Several types of photochemical reactors are currently employed to effect the photocatalytic reactions, with varying success. One style of reactor positions a light source within a transparent receptacle extending into the reactant solution, as shown in U.S. Pat. No. 3,628,010. Such an arrangement enables the light source to be positioned in close proximity to a photocatalyst dispersed within the reactant solution. This is particularly useful when the reactant solution is light absorbing, which would otherwise reduce the quantity of light received by the photocatalyst. An inherent problem in such an arrangement, however, is that because a thin wall receptacle or tube is required to house the activating light the internal pressures within the reaction chamber must be kept at a minimum so as not to rupture the receptacle. Thus, in situations where it is preferable to conduct the photochemical reaction under a substantially increased pressure, thereby providing a greater concentration of a gaseous component in the reactant solution within the reaction chamber for a more efficient reaction, this arrangement is totally unsuitable.
An additional problem in this arrangement is found in the size limitation of the light source. Particularly, because of the restricted area available to house the light source within the receptacle, the light source is limited to a substantially small, and correspondingly expensive, configuration. Furthermore, because of its location with respect to the reaction chamber, it may be necessary to disassemble a substantial portion of the reactor to effect routine maintenance and replacement of the light source.
Another style of photochemical reactor is more suitable for operating at elevated pressures. This style of reactor employs an external light source positioned relative to a thick, pressure resistant, transparent window which permits the irradiation of the reactant solution. The inherent problem with this embodiment, however, is that if the reactant solution is light absorbing, insufficient light radiation will reach a photocatalyst dispersed therein such that the photocatalytic reaction will not occur or will occur inefficiently. This being the case, the advantageous properties of a photocatalyst are lost. Furthermore, depending upon the location of the window relative to the configuration of the reaction chamber, it may not be possible to fully irradiate the entire volume of the chamber completely. As such, a less efficient reaction would occur as compared to that normally associated with a fully irradiated chamber.
Despite the various photochemical reactors curently used in performing photochemical reactions, none embodies the desirable attributes of a light-immersion type reactor coupled with the desirable attributes of a high pressure reactor. Namely, no photochemical reactor, as yet, has enabled the photochemical reaction to take place under extremely high internal pressure, occasionally in excess of 340 atmospheres, while at the same time permitting the activating light to be introduced into the reaction chamber with means for transmitting light immersed within the reactants so as to permit the activating light to be dispersed in a controlled manner therein.